1. Field of the Invention
The present invention relates to an improved method for the manufacture of sliders. More particularly, the invention relates to an improved method for forming the air bearing surface (ABS) of a slider.
2. Description of the Background Art
Digital magnetic recording devices for data storage generally comprise a thin film magnetic recording disk and a head or transducer which is moved above the surface of the rotating disk to electromagnetically read and write information on the disk. Advanced thin film magnetic recording disks generally comprise a rigid substrate, a magnetic layer such as a cobalt-based metal alloy, a protective amorphous carbon layer and a lubricant layer, such as a perfluoropolyether disposed on the carbon overcoat.
During operation of the disk drive system, an actuator mechanism moves the magnetic transducer to a desired radial position on the surface of the rotating disk where the head electromagnetically reads or writes data. Usually, the head is integrally mounted in a carrier or support referred to as a xe2x80x9csliderxe2x80x9d. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air and, therefore, to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions (air bearing pattern) on the air bearing surface (ABS) which enable the slider to fly at a constant height close to the disk during operation of the disk drive.
The recording density of a magnetic disk drive is limited by the distance between a transducer and the magnetic media. One goal of air bearing slider design is to xe2x80x9cflyxe2x80x9d a slider as closely as possible to a magnetic medium while avoiding physical impact with the medium. Smaller spacings, or xe2x80x9cfly heightsxe2x80x9d, are desired so that the transducer can distinguish between the magnetic fields emanating from closely spaced regions on the disk.
In manufacturing such read/write heads, a large number of sliders are fabricated from a single wafer having rows and columns of the magnetic transducers deposited simultaneously on the wafer surface using semiconductor-type process methods. In one process embodiment, after deposition of the heads is complete, the wafer is cut into four quadrants. Each quadrant is then bonded to a lapping fixture and grounded on a lapping plate to provide accurate head dimensions. After lapping, single row bars of sliders in side by side orientation are cut from the wafer quadrant. These row bars can optionally be lapped again, and the ABS design is formed in each slider using art-known lithographic and dry etching techniques. The ABS is formed by coating the slider surface with a thick layer of protective photoresist, imaging the photoresist with radiation; development of the ABS image in the photoresist and dry etching (transferring) the ABS image into the body of the slider. After the ABS has been formed, the remaining photoresist is removed by solvent or soda blast. Lastly, the row bars are adhered to suitable tape; and each bar is diced, i.e., separated with a diamond-cut saw into individual sliders, each having a magnetic head terminating at the ABS. Each slider is then attached to an actuator for use in a magnetic disk drive.
It has been determined that damage can occur to the thin film magnetic sensor during the above described process steps. Grill et al. in U.S. Pat. No. 5,159,508, disclose a dry process for forming a protective coating over the slider prior to the lithographic process. The protective coating comprises two layers, the first layer an adhesion layer, e.g. silicon and a second layer of amorphous carbon. The ABS is then formed in the slider covered with the protective coating. Grill teaches that protective coating should be permanently retained on the slider because the top layer of protective carbon will protect the slider from mechanical damage during subsequent normal operation of the slider. Unfortunately, due to pinholes and defects in the photoresist layer, the carbon layer of the protective coating is, in some cases, damaged during the etching process. This damage to the carbon layer can cause corrosion of the sensor resulting in diminished signal amplitude during operation of the disk drive. Chang et al. U.S. Pat. No. 5,271,802, teaches a similar process where the top layer of the protective coating of the slider is silicon oxide. Although silicon is not as easily damaged as carbon during the etching process, silicon oxide is not a suitable protective coating for sliders because of its relatively poor wear resistance.
Therefore, there is still a need in this art for a slider manufacturing process which results in sliders having suitable permanent protective coatings over the ABS.
It is, therefore, an object of the present invention to provide an improved method for the manufacturing of magnetic sliders. Other objects and advantages will become apparent from the following disclosure.
The present invention relates to a method for producing magnetic sliders having a permanent protective coating of carbon over the ABS. The method generally comprises the steps of: (a) depositing a protective coating on a surface of the slider, the protective coating comprising an underlayer of carbon and a top layer selected from silicon and titanium; (b) depositing a photoresist layer onto the protective coating; (c) imagewise exposing the photoresist layer to radiation; (d) developing the image in the photoresist layer to expose the protective coating; (e) transferring the image through the protective layer and into the slider to form the air bearing pattern in the slider; and (f) removing the top layer of the protective coating.
The method provides a slider having uniform protective coating of carbon over the ABS surface of the slider.
A more thorough disclosure of the present invention is presented in the detailed description which follows and the accompanying figures.